The present invention relates to a hose with corrugated metal tube, which is suitable for fuel conveying hose for automobiles, refrigerant conveying hose or any other fluid conveying hose, and more particularly to a hose with corrugated metal tube including characteristic reinforced layer.
Typical rubber hoses, for example, made of blended product of acrylonitrile-butadiene rubber and polyvinyl chloride (NBR/PVC blend) which is excellent in resistance to gasoline permeability, have been used for conveying fuel for automobiles or the like in view of their high vibration-absorbability, easy assembling or the like. However, for the purpose of global environment protection, the regulations have been recently tighten against permeation of fuel for automobiles or the like, and are anticipated to be further tighten in the future. Further, hoses are demanded to meet the requirements to convey highly permeable fluid such as hydrogen gas used in fuel cells or carbon dioxide (CO2) refrigerant.
Then it is anticipated difficult to satisfy the future requirements with hoses made only of organic materials such as rubber or resin.
Accordingly, it is currently considered to adapt a hose with a corrugated metal tube as an inner layer because the hose with corrugated metal tube is expected to have an extremely high fluid impermeability to meet the demand for a fluid impermeable hose.
As for a hose with corrugated metal tube, such hoses as disclosed in the following Document 1, Document 2 and Document 3 are known.
Document 1JP, A, 2001-182872Document 2US20020007860A1Document 3JP, U, 51-150511
In case of the hose with corrugated metal tube, even if adapted for hydrogen gas used for fuel cells, a corrugated metal tube in or as an inner layer reduces gas permeation zero, i.e., completely eliminates permeation of gas.
However, if the hose with corrugated metal tube is adapted, it will be a problem how to construct a reinforcing structure with a reinforced layer.
As shown in FIG. 6, a typical conventional hose usually has a hose body 200 of multi-layered construction including inner elastic layer 202, reinforced layer 204 and outer elastic layer 206. The reinforced layer 204 is constructed by reinforcing filament member or reinforcing filament members. If a winding or braid angle of reinforcing filament member or reinforcing filament members in the reinforced layer 204 or a winding or braid angle thereof with respect to an axial direction is higher or larger than a neutral angle α (refer to FIG. 6 (B)), which of reinforcing filament member or reinforcing filament members is 54 degrees 44 minutes (54° 44′) in this case, the reinforced layer 204 overall expands or elongates longitudinally, extracts and deforms in a radial or diametrical direction so as to make a braid or winding angle of reinforcing filament member or reinforcing filament members close to or to be a neutral angle α when an internal pressure is exerted thereto as shown in FIG. 7 (A). Here and so forth, it is based on the hypothesis that reinforcing filament member itself or reinforcing filament members themselves do not elongated. And in “braid angle” of FIG. 7 a winding angle is also included.
On the contrary, as shown in FIG. 7 (C), if a braid or winding angle of the reinforcing lament member or the reinforcing filament members in the reinforced layer 204 are lower or smaller than a neutral angle α, the hose including the reinforced layer 204 overall contracts in a longitudinal direction and expands and deforms in a radial direction so as to make a braid or winding angle thereof close to or to be a neutral angle α when an internal pressure is exerted thereto.
And, as shown in FIG. 7 (B), if a braid or winding angle of reinforcing filament member or reinforcing filament members in the reinforced layer 204 is initially a neutral angle α, the reinforcing filament member or the reinforcing filament members remain at an angle α or a neutral angle α as it was when an internal pressure is exerted thereto. Therefore, the hose overall does not substantially expand and contract in a longitudinal direction, and also does not substantially expand and contract in a radial direction.
In FIG. 6, a numeral reference 208 indicates a rigid pipe-shaped connecting part inserted in the hose body 200 on an axial end portion thereof, a numeral reference 210 a metallic socket fitting fitted onto or on an outer surface of the hose body 200. The hose body 200 is fixedly secured to the connecting part 208 and the socket fitting 210 while clamped radially in between the connecting part 208 and the socket fitting 210, by securely compressing or swaging the socket fitting 210 radially inwardly thereto.
In FIG. 6, a numeral reference 212 indicates an inwardly directed collar-like portion formed on an axial end of the socket fitting 210. In this state, the collar-like portion 212 fits in and engages with a fit-engagement groove formed on an outer surface of the connecting part 208.
As stated above, in general, a typical conventional hose tends to expand, contract and deform in radial and longitudinal directions depending on a braid or winding angle of a reinforced layer when an internal pressure is exerted thereto.
However, a hose including a corrugated metal tube 214 as inner layer as shown in FIG. 8 tends to expand and deform uniformly in a longitudinal direction regardless of a braid or winding angle of a reinforced layer when an internal pressure is exerted thereto.
Therefore, such hose with corrugated metal tube inherently involves a problem that when an internal pressure is exerted thereto repeatedly, the hose including the corrugated metal tube 214 overall repeatedly elongates or expands in a longitudinal direction, and consequently repeated deformation thereof causer a fatigue break in the corrugated metal tube 214.
The above are described with reference to a hose for conveying hydrogen gas used in a fuel cell as example. The similar problems are anticipated in common to any hoses. For example, it may be the case that a hose with corrugated metal tube is employed for conveying fuel gasoline for the purpose to deal with gasoline or the like permeating to an air or, for high temperature and high pressure application due to high output power of equipment, where low permeation is severely regulated. Or it may be the case that a hose with corrugated metal tube is employed to convey carbon dioxide (CO2) as refrigerant fluid, which is low in amount of particles just like hydrogen and has high gas permeation. Further, it may be any other case that a hose with corrugated metal tube is applied in fields under severe regulations against gas permeation.
It is an object of the present invention to provide a hose with corrugated metal tube to settle the problems described above.